An optical measurement system comprises a first housing body and a second housing body which can be rotated relative to the first housing body about a second axis of rotation, wherein the second housing body contains a measurement telescope, an inner roller bearing support fixed to the second housing body and protruding into the first housing body; an outer roller bearing support fixed to the first housing body; a drive disc fixed to the inner roller bearing support; wherein a motor having a motor shaft is attached to the first housing body in such a way that the motor shaft or a wheel fixed to the motor shaft is positioned on the drive disc and is pressed against said disc by a spring force orientated transversely to the second axis of rotation, and wherein the motor shaft or the wheel is coupled to the drive disc in a frictional fit.
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1. Optical measurement system, comprising:
a base,
a first housing body which can be rotated relative to the base about a first axis of rotation;
a second housing body which can be rotated relative to the first housing body about a second axis of rotation;
wherein the first axis of rotation and the second axis of rotation are orientated transversely to one another;
wherein the second housing body contains a measurement telescope, the measurement axis of which is orientated transversely to the second axis of rotation;
wherein the measurement system further comprises:
an inner roller bearing support fixed to the second housing body and protruding into the first housing body;
an outer roller bearing support fixed to the first housing body;
a first roller bearing and a second roller bearing, the inner rings of which are fixed to the inner roller bearing support at a distance from one another, symmetrically about the second axis of rotation, wherein outer rings of the roller bearings are fixed to the outer roller bearing support, wherein the first and the second roller bearing are biased in an o arrangement;
a drive disc fixed to the inner roller bearing support;
a motor having a motor shaft;
wherein the motor is attached to the first housing body in such a way that the motor shaft or a wheel fixed to the motor shaft is positioned on the drive disc and is pressed against said disc by a spring force orientated transversely to the second axis of rotation,
wherein the motor shaft or the wheel is coupled to the drive disc in a frictional fit, and
wherein no further bearings are provided aside from the first and second roller bearings to mount the second housing body relative to the first housing body.
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This application claims priority to German Application No. 10 2013 022 018.1, filed Dec. 20, 2013, the entire contents of which are incorporated herein by reference in their entirety for all purposes.
The present invention relates to optical measurement systems, for example optical measurement systems for angle measurement in the field of geodesy, theodolites, total stations or the like.
For angle measurement in the field of geodesy, optical measurement systems are frequently used. These measurement systems are distinguished in that the angle measurement can be carried out with a very high level of precision. To achieve the required precision, the measurement systems themselves must be manufactured highly precisely. Optical measurement systems of this type, such as theodolites, total stations or the like, usually comprise at least a measurement telescope and a housing body, which can be rotated relative to one another about an axis of rotation. Usually, the measurement telescope is mounted on opposite sides of the measurement telescope by a shaft in the housing body. If this shaft is in a single piece and mounted in the housing body at both ends, the measurement axis of the measurement telescope is arranged eccentrically with respect to the shaft, in such a way that rotating the shaft displaces the measurement telescope in position and orientation. The simultaneous displacement of the position and orientation of the measurement telescope when the shaft rotates has a negative effect on the measurement process and the measurement precision. Alternatively, the measurement telescope is conventionally mounted in the housing body by journal shafts arranged on opposite sides of the measurement telescope, in such a way that the measurement axis of the measurement telescope is displaced exclusively in orientation, but not in position, when the journal shafts rotate. However, it is expensive to produce and adjust a measurement telescope mounted by two journal shafts.
An object of the present invention is therefore to propose an optical measurement system which overcomes the aforementioned drawbacks of mounting a measurement telescope in a housing body.
In embodiments of the invention, an optical measurement system comprises a base; a first housing body which can be rotated relative to the base about a first axis of rotation; and a second housing body which can be rotated relative to the first housing body about a second axis of rotation; the first axis of rotation and the second axis of rotation being orientated transversely, in particular orthogonally, to one another; the second housing body containing a measurement telescope, the measurement axis of which is orientated transversely, in particular orthogonally, to the second axis of rotation; the measurement system further comprising: an inner roller bearing support fixed to the second housing body and protruding into the first housing body; an outer roller bearing support fixed to the first housing body; a first roller bearing and a second roller bearing, the inner rings of which are fixed to the inner roller bearing support at a distance from one another, symmetrically about the second axis of rotation, outer rings of the roller bearings being fixed to the outer roller bearing support, the first and second roller bearings being biased in an O arrangement; a drive disc fixed to the inner roller bearing support; a motor having a motor shaft; the motor being attached to the first housing body in such a way that the motor shaft or a wheel fixed to the motor shaft is positioned on the drive disc and is pressed against said disc by a spring force orientated transversely, in particular orthogonally, to the second axis of rotation, the motor shaft or the wheel being coupled to the drive disc in a frictional fit, and no further bearings, in particular roller bearings, being provided aside from the first and second roller bearings to mount the second housing body relative to the first housing body.
As a result, the second housing body, which contains the measurement telescope, is mounted in the first housing body merely on one side, and, apart from the first and second roller bearings, the measurement system is free of further bearings which are used for mounting the second housing body relative to the first housing body. When the second housing body is rotated about the second axis of rotation relative to the first housing body, the measurement axis of the measurement telescope can be displaced exclusively in orientation but not in position, making simple, precise angle measurement possible. As a result of the first and second roller bearings being biased in an O arrangement, the inner roller bearing support is arranged stably and rotatably in the outer roller bearing support, ensuring the required precision during the rotation of the first housing body relative to the second housing body. In addition, the manufacture of the one-sided mounting of the second housing body in the first housing body is simpler and more favourable than a two-sided mounting, for example by way of a single-piece shaft or two journal shafts. A drive disc is fixed to the inner roller bearing support and is coupled in a frictional fit, in particular not in a positive fit, to a motor shaft of a motor or to a wheel fixed to the motor shaft, so as to displace the orientation of the inner roller bearing support, and thus the orientation of the second housing body relative to the outer roller support bearing and thus relative to the first housing body, in a controllable manner.
The first housing body may be mounted in the base in the same way, it being possible for the inner roller bearing support to be fixed to the first housing body and the outer roller bearing body to be fixed to the base or for the inner roller bearing support to be fixed to the base and the outer roller bearing support to be fixed to the first housing body, and all further components being arranged analogously in relation to the arrangement of the roller bearing supports, in such a way that the first housing body is likewise mounted rotatably relative to the base and is adjustable by a friction wheel drive.
In exemplary embodiments, the drive disc may consist of a plastics material, in particular PET, or ceramics and have a rubberised surface. Further, the drive disc may comprise a tyre of a plastics material, in particular PET or a rubber, against which the motor shaft or the wheel is pressed. As a result, it is possible to set the required friction between the drive disc and the motor shaft. The tyre is thus directly in contact with the motor shaft or a wheel fixed to the motor shaft. The tyre and the drive disc may consist of one piece.
In exemplary embodiments, the motor shaft or the wheel consists of metal.
In exemplary embodiments, the motor shaft is orientated substantially parallel to the second axis of rotation. In this arrangement, the area between the motor shaft or the wheel and the drive disc, via which the frictional forces are transmitted, is large, leading to a particularly good frictional fit between the motor shaft or the wheel and the drive shaft.
In exemplary embodiments, the motor is attached to the first housing body in such a way that the motor shaft is freely pivotable about at least one pivot axis, which is orientated transversely, in particular orthogonally, to the second axis of rotation. As a result, the motor shaft or the wheel can be orientated optimally with respect to the drive disc. In particular, two pivot axes about which the motor is freely pivotable may be provided, the two pivot axes and the two axes of rotation being orientated transversely, in particular substantially orthogonally, to one another.
Further, damping elements may be arranged in or on components of the friction wheel drive, in particular the motor or a suspension of the motor, so as to damp vibrations and oscillations of the friction wheel drive.
In exemplary embodiments, the first and second roller bearings, as seen in the direction of the second axis of rotation, are arranged between the second housing body and the drive disc. As a result, the inner roller bearing support is arranged stably and rotatably relative to the outer roller bearing support.
In exemplary embodiments, the optical measurement system further comprises an angle measurement system for measuring a rotational position of the second housing body relative to the first housing body about the second axis of rotation. As a result, the rotational position of the second housing body relative to the first housing body, in other words the orientation of the second housing body relative to the first housing body, about the second axis of rotation can be measured.
In further exemplary embodiments, the angle measurement system comprises an encoder disc, which is fixed to the inner roller bearing support, and a sensor, which senses the encoder disc and is fixed to the outer roller bearing support.
In further exemplary embodiments, the encoder disc, as seen in the direction of the second axis of rotation, is arranged between the drive disc and the first roller bearing. This configuration makes high-precision determination of the rotational position of the second housing body relative to the first housing body about the second axis of rotation possible, since the encoder disc is fixed to the inner roller bearing support at a point which is particularly resistant to tilts of the inner roller bearing support, in other words has a particularly stable orientation.
In further exemplary embodiments, the encoder disc may consist of a glass, a ceramic or a plastics material. As a result, the encoder disc can be relatively light and resistant for example to temperature fluctuations.
In further exemplary embodiments, the optical measurement system further comprises a control system, which drives the motor as a function of measurement signals of the angle measurement system. As a result, a control circuit can be implemented which for example keeps the rotational position of the second housing body in a stable rotational position relative to the first housing body about the second axis of rotation or adjusts it by a predetermined amount. In this way, the control system can act as a self-regulation system.
In exemplary embodiments, the first and second roller bearings are each formed as a ball bearing or the like.
In exemplary embodiments, a ratio between the diameter of the roller body and a maximum distance between two roller bodies of a roller bearing in the first and second roller bearings is less than 0.15, in particular less than 0.07. As a result, high stability between the inner ring and the outer ring of each first and second roller bearing is ensured, increasing the stability and precision of the mounting of the inner roller bearing support.
Further, the outer roller bearing support and the outer rings of the roller bearing may be glued together and/or the inner roller bearing support and the inner rings of the roller bearing may be glued together, so as to eliminate mechanical play.
In exemplary embodiments, the second axis of rotation passes through a light beam, which extends in the measurement telescope and is used for imaging. In particular, when the light which extends in the measurement telescope and is used for imaging is arranged along an optical axis of the measurement telescope, rotating the measurement telescope about the second axis of rotation substantially only displaces the orientation of the light beam, meaning that the measurement process can be carried out simply and precisely.
In exemplary embodiments, the measurement axis intersects the second axis of rotation. When rotated about the second axis of rotation, the measurement axis is thus displaced exclusively centrically about the second axis of rotation, this being particularly advantageous for the measurement process.
In exemplary embodiments, the measurement axis intersects the first axis of rotation. When rotated about the first axis of rotation, the measurement axis is thus displaced exclusively centrically about the first axis of rotation, this being particularly advantageous for the measurement process.
In exemplary embodiments, the first housing body is of an L-shaped formation. As a result, the second housing body and/or the measurement telescope can be fixed and adjusted particularly simply on the inner roller bearing support.
In exemplary embodiments, the first housing body comprises a first housing part, which extends parallel to the first axis of rotation and is arranged at a distance from the first axis of rotation and on which the outer rings of the roller bearings are fixed.
In further exemplary embodiments, the first housing body comprises a second housing part, which extends parallel to the first axis of rotation and is arranged opposite the first housing part with respect to the first axis of rotation. As a result, further components can be arranged in the second housing part of the first housing body. In this configuration, the first housing body is of the conventional U-shaped formation.
In further exemplary embodiments, the second housing body, as seen in the direction of the second axis of rotation, is arranged between the first and second housing parts of the first housing body. As a result, the second housing body, which contains the measurement telescope, is enclosed by the first and the second housing part, meaning that the second housing body is protected in part from external influences.
In further exemplary embodiments, the second housing part contains a battery.
Further features of the invention may be taken from the following description of embodiments in connection with the claims and the drawings. In the drawings, like or similar elements are denoted by like or similar reference numerals. It is noted that the invention is defined by the scope of the accompanying claims, and is not limited to the embodiments of the disclosed examples. In particular, the individual features of embodiments according to the invention may be implemented in different numbers and combinations from in the examples discussed in the following. The following description of an embodiment of the invention makes reference to the accompanying drawings, of which embodiments of the invention are described in the following by way of drawings, in which:
Further, a drive disc 35 is fixed to the inner roller bearing support 23, and is used for controlling and regulating a rotational position of the inner roller bearing support 23. The drive disc 35 comprises a tyre 36, which consists of a plastics material, in particular PET or a rubber, and which is directly in contact with the wheel.
The optical measurement system 1 further comprises a motor 37 having a motor shaft 39. A wheel 41 is attached to the motor shaft 39, and the motor 37 is attached to the first housing body 9 by way of a suspension 43 in such a way that either the wheel 41 fixed to the motor shaft or the motor shaft 39 itself is positioned on the drive disc, the motor shaft 39 or the wheel 41 being pressed against the drive disc 35 by spring force orientated transversely to the second axis of rotation 31. As a result, the motor shaft 39 or the wheel 41 is coupled to the drive disc 35 by frictional fit, in other words a transfer of frictional forces and torques between the motor shaft 39 or the wheel 41 and the drive disc 35 by friction is made possible. By contrast with a coupling using gearwheels, in this embodiment the coupling is achieved exclusively by frictional fit and not by positive fit. An exact configuration of the transmissible torques can be set for example by selecting the materials of the motor shaft 39 or of the wheel 41 and of the drive disc 35 or of the tyre 36 attached to the drive disc. In particular, the motor shaft 39 or the wheel 41 may consist of metal.
As is shown in
For displacing the first housing body 9 relative to the base 7, the measurement system further comprises a drive 46, which may in particular be constructed analogously to the above-disclosed friction wheel drive.
To mount the measurement telescope 21 contained in the second housing body 19 in a stable and rotatable manner in the first housing body 9, the first roller bearing 25 and the second roller bearing 27, as seen in the direction of the second axis of rotation 31, are preferably arranged between the second housing body 19 and the drive disc 35.
The optical measurement system 1 further comprises an angle measurement system 47, by means of which a rotational position of the second housing body 19 relative to the first housing body 9 about the second axis of rotation 31 can be measured. In this embodiment, the angle measurement system 47 comprises an encoder disc 49, which is fastened to the inner roller bearing support 23, and a sensor 51, which senses the encoder disc and is fixed to the first housing body 9. Alternatively, the sensor 51 may also be fixed to the outer roller bearing support 29.
The angle measurement system 47 is completely enclosed by the first housing body 9, meaning that the angle measurement system 47 is protected from external influences, for example dust, moisture or the like. Preferably, the encoder disc 49, as seen in the direction of the second axis of rotation 31, is arranged between the drive disc 35 and the first roller bearing 25. As a result, the encoder disc 49 is fixed to a position on the inner roller bearing support 23, which is particularly stable as regards tilting of the inner roller bearing support 23 in the context of mechanical play, this contributing to the precision of the angle measurement.
The optical measurement system 1 further comprises an angle measurement system 48 which is used for determining the relative rotational position of the first housing body 9 and the base 7. The angle measurement system 48 may in particular have an analogous construction to the angle measurement system 47.
The optical measurement system further comprises a control system 53, which can drive the motor 37 as a function of measurement signals of the angle measurement system 47. This makes active control and regulation of the rotational position of the second housing body 19 relative to the first housing body 9 possible, in that the control system 53 detects the measurement signals of the angle measurement system 47 and actuates the motor 37 accordingly. In this way, the rotational position can be regulated in such a way that the rotational position is kept constant in spite of being subject to external influences. Alternatively, the rotational position can be adjusted through a predetermined angle by way of the control/regulation.
As is shown in
The first housing body 9 is of an L-shaped formation, the first housing body 9 comprising a first housing part 57 which extends substantially parallel to the first axis of rotation 11 and is arranged at a distance from the first axis of rotation 11. The first housing body further comprises a second housing part 59, which extends substantially parallel to the first axis of rotation 11 and is arranged opposite the first housing part 57 with respect to the first axis of rotation 11. The second housing part 59 may comprise further components, and can be fixed to a third housing part 61, which is rigidly connected to the first housing part 57. As is shown in
A ratio of a diameter d of the roller body 71 to a maximum distance D between two roller bodies in the first roller bearing 25 and the second roller bearing 27 may take values which are particularly advantageous for stable mounting. Said ratio is particularly advantageous if it is less than 0.15, in particular less than 0.07.
The roller bearings may for example be configured as ball bearings or the like, and may in particular be identical.
Hahn, Wolfgang, Vogel, Michael, Laabs, Steffen, Fischer, Mario, Korn, Thomas, Kötzing, Michael
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Dec 08 2014 | KORN, THOMAS | Trimble Jena GmbH | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 034607 | /0657 | |
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